First, an observation: this thing is thin! So thin that there is literally no room for the 5 MP camera in the iPhone 4.

Second, some news: The 4th Generation iPod Touch’s A4 processor package has the same 256 MB Samsung SDRAM markings found on the iPad’s processor. Many developers will be disappointed that it doesn’t have the 512 MB found in the iPhone 4, but Apple had to keep costs down to hit the $229 price point.

We found several notable improvements from the previous Touch, especially a more repair-friendly front panel that can be easily removed with a heat gun and some careful prying. This is by far the easiest Touch to open, although it’s not completely straightforward once you get inside.

This is the easiest iPod Touch we’ve ever cracked open — a bit of glue and two tabs hold the front panel in place. We hoped that the insides would continue to be repair-friendly, but then found that the front glass and LCD panel were permanently fused together. This will prevent dust from getting beneath the glass, but unfortunately will also make repair more expensive.

Like all other revisions of the iPod Touch, the battery is soldered to the logic board. This isn’t a surprise given the slim form factor of the iPod, but we wish Apple would make battery replacement easier, especially on a Touch that is now easier to open.

Apple did add more space between the battery’s three solder points compared to the 3rd Gen Touch. This should make the soldering job a little easier when replacing the battery, as there’s less chance of accidentally bridging the contacts.

The EMI shield is surprisingly heavy, weighing in at 11 grams. The entire iPod Touch is only 101 grams, meaning Apple has devoted more than 10% of the iPod’s weight to this metal EMI shield.

Unfortunately, the rear-facing camera is only 960×720 resolution. That’s only about .7 megapixels, compared to 5 megapixels on the iPhone 4. Apple was forced to sacrifice still photo resolution in order to squeeze the camera into the Touch’s slim package. Going forward, we expect Apple to adopt improved micro camera technology as better cameras come to market.

For those of you who are wondering, there’s no way the iPhone 4’s rear camera can be installed in the Touch.

In a first for the iPod Touch line, the headphone jack is not soldered to the logic board. There’s also a liquid damage indicator on the bottom of the headphone jack, so don’t use your Touch to stir the coffee.

This primary antenna is situated near the front glass panel. Its new location eliminates the need for the plastic “window” found on the 3rd generation Touch. There also appears to be a secondary antenna located on the headphone jack.

Contrary to Apple’s initial claims on their FaceTime marketing page, the iPod Touch does not have a vibrator. Apple’s website has been updated to remove this claim.